A transfer press typically includes a series of work stations in a press machine body which are operable to press form a workpiece sequentially.
Also provided in the press machine body is a transfer feeder that is designed to successively carry a workpiece from one of these work stations to another.
Such a transfer feeder includes a pair of transfer bars or lift beams arranged in parallel and extending in a workpiece transfer direction in which a finger means secured to the transfer bars or a cross bar means secured to the lift beams via the cross bar carriers serves to hold a workpiece which is sequentially transferred to these work stations as the transfer bar or the lift beam pair is driven to move two- or three-dimensionally.
On the other hand, the transfer feeder referred to above may be implemented in a form in which an operating mechanism such as for a feed, lift and clamp function can be driven with a power taken from the press machine proper.
Such mechanisms are typically installed at a site on upstream or at a floor side downstream of the press machine. Where these mechanisms are located at the floor or bed side, an inconvenience has hitherto been met that they may cause a trouble in installing a work carrying in unit for conveying a workpiece into the press machine or installing a work carrying out unit for conveying a workpiece out of the press machine.
In an attempt to remove such an inconvenience, a modification in the transfer feeder has been proposed, as disclosed, for example, in Japanese Unexamined Patent Publication Nos. Hei 6-218458 and 6-218459, in which a feed mechanism or a lift mechanism is placed on or above the press machine.
In a transfer feeder as described in these patent publications, the lift beams are vertically driven by a lift mechanism with a servo motor as a drive source, a feed mechanism which comprises a feed cam rotatable by a power taken from the press machine and the feed lever adapted to be oscillated by such a feed cam is set up at a site upstream of the press machine body and the feed mechanism is operated to drive a cross bar carrier assembly supported on the lift beams in a feed direction.
Also, in a transfer feeder as described in the above identified patent publications, a feed cam and a feed lever of the feed mechanism are accommodated in a cam box that is installed at a site upstreams of the press machine body, and the upper end side of the feed lever is supported by a shaft in the cam box whereas the lower end side of the feed lever is allowed to project downwards of the cam box, through an elongate opening formed in a lower wall of the cam box and elongated in the feed direction. And, the lower of the feed lever and the cross bar carrier that is located at an uppermost stream side are coupled together.
It should be noted at this point that in such a conventional transfer feeder as just referred to above, a portion of the lubricating system in a press machine is piped locally in such a cam box of the feed mechanism, and various bearing or sliding parts such as a cam shaft and shaft bearing parts, and sliding parts of a cam follower which are attached to a feed cam and a feed lever are thereby lubricated. And, the lubricating oil that flows down from the bearing and sliding parts is allowed to collect in an oil pan mechanism provided on the bottom of the cam box, and thereafter is returned to the lubricating system.
The cam box is commonly formed through its bottom wall with an elongate opening that is required to allow the feed lever to oscillate. Because of such a construction, a portion of the oil is allowed to flow down from the bearing and sliding parts in the cam box and then to fall on a workpiece being introduced into the press machine body, tending to hinder an operation required and to contaminate the workpiece, an inconvenience produced.
It is accordingly an object of the present invention to eliminate such an inconvenience encountered in the prior art and to provide an oil or hydraulic leakage proof apparatus in a transfer feeder, which effectively prevent an oil from flowing down through an opening in the bottom wall of a cam box, which in turn prevents any portion of the oil from contaminating a workpiece or any part of the press machine and from hindering an operation thereof.